1. Field of the Invention
The present invention relates to a centrifugal fan.
2. Description of the Related Art
In the related art, for the purpose of a decrease in thickness and size, a centrifugal fan has been proposed in which an impeller is received in a casing having a suction port and an air outlet (for example, see JP-A-2012-180810). In the configuration disclosed in JP-A-2012-180810, since an impeller is disposed in a casing, a draft angle is formed in outer-diameter portions of blades constituting the impeller, and the length of a cross-section in the vicinity of a suction port can be reduced, a wind speed is increased by efficiently sending wind suctioned from the suction port to the outer-diameter side (see FIG. 10 of JP-A-2012-180810).
However, in the centrifugal fan disclosed in JP-A-2012-180810, the draft angle of each blade is formed to have the same draft angle about the draft direction above and below a main plate. Accordingly, when an amount of air suctioned from the suction port varies above and below due to an influence of an opening area of the suction port below the blade, unevenness in wind speed occurs in the entire blade and thus there is a problem in that an air flow rate cannot be increased.